Although the incidence of degenerative changes in the blood vessels is well known to increase with advancing age, quantitative data on the changes in peripheral blood flow due to the aging process per se are lacking. Venous occlusion plethysmography has been shown to be the most accurate and reproducible method to measure peripheral arterial flow. We have used this method to evaluate peripheral blood flow in healthy subjects aged 20-83 years from the Baltimore Longitudinal Study of Aging (BLSA) both at rest and in response to post-occlusion hyperemia, which results in near-maximal flow. Neither resting nor post-occlusion hyperemic blood flow were related to age in these 146 BLSA men and women who underwent occlusions of 1, 2, and 3 minutes both at 26 degrees C and 35 degrees C. These results suggest that peripheral arterial flow is not limited by age per se in man. In a second protocol, the response of peripheral blood flow to intravenous infusion of isoproterenol and sodium nitroprusside was determined by plethysmography in 25 healthy volunteers ages 25- 84 years. The results of this study are pending.